1. Field of the Invention
The present invention relates a controller for a three-wheel turbocharger and, more particularly, to an improved controller which utilizes identified engine parameters to control the flow of engine oil or turbocharger hydraulic fluid to the third turbine wheel on a turbocharger which, in turn, maintains a minimum absolute pressure within an engine manifold under all dictated conditions.
2. Discussion of the Prior Art
A turbocharger having a third wheel for supplementing the energy provided to turn the turbocharger during engine operation when additional airflow is required is shown in U.S. Pat. No. 4,285,200, which issued Aug. 25, 1981, by J. L. Byrne et al., which is assigned to the Garrett Corporation. This patent discloses a control valve which is controlled by the compressor discharge pressure.
In a later filed continuation-in-part of the above-identified Byrne et al. patent, the use of an auxiliary combustor which is mounted between an engine and the turbocharger is disclosed. This combustor receives fuel from the engine fuel supply and air from a bypass between the turbocharger and the engine to provide a boost to the turbine wheel of the turbocharger during starting conditions. The patent also describes alternative methods for boosting the RPM of the turbocharger during starting conditions including a high pressure pump or a high pressure oil accumulator. See U.S. Pat. No. 4,322,949, which issued Apr. 6, 1982, by J. L. Byrne et al. assigned to the Garrett Corporation.
In U.S. Pat. No. 4,444,014, issued Apr. 24, 1984, by R. J. Kobayashi et al., assigned to the Garrett Corporation, there is disclosed a control arrangement which uses a dual function control valve responsive to engine speed and load to regulate the supply of hydraulic fluid to the third wheel of the turbocharger. The control valve is responsive to increasing hydraulic pressure which is proportional to engine speed. The control valve is driven by a diaphragm which adjusts the valve in proportion to the engine load utilizing the differential between the engine sump pressure and the pressure of the charge air on the output side of the turbocharger compressor.
U.S. Pat. No. 4,478,043, issued Oct. 23, 1984, by R. J. Kobayashi et al , assigned to the Garrett Corporation, is substantially similar to the U.S. Pat. No. 4,444,014 but includes method claims.
U.S. Pat. No. 4,622,817, issued Nov. 18, 1986, by R. J. Kobayashi, assigned to the Garrett Corporation, discloses a control circuitry similar to that shown in the two U.S. Pat. Nos. 4,444,014 and 4,478,043 mentioned immediately above. This later patent further discloses a pilot controller or solenoid operated valve which is controlled by an electrical master control unit that receives input signals including speed determined by a tachometer and pressure determined by the compressor discharge pressure.